The search for a missing five-year-old girl continues after British police arrested a 46-year-old man on suspicion of abduction.

April Jones, who was playing with friends in the Welsh town of Machynlleth, willingly got into a van about 7pm Monday (7am yesterday, NZ time).

Police confirmed the man arrested was known to the girl's family.

Detective Superintendent Reg Bevan of Dyfed-Powys police said shortly before 5pm (5am NZ time): "We are continuing our investigation to find April, however within the last hour we have arrested a 46-year-old male from the Machynlleth area who is being detained at Aberystwyth police station," the Daily Telegraph reported.

"We made the arrest just outside Machynlleth and we are hopeful that this individual will assist us in locating April, who is still missing.

"We are still pursuing all lines of enquiry, with a view that she is still alive, and we will continue to do so until we find her."

Bevan said the arrested man was a local and had vehicle similar to the one seen by witnesses, the Telegraph reported.

They had found him walking on the side of the road and later found his vehicle in Machynlleth.

Police launched a massive search after April was reported missing, evening using teenagers from the town's high school to help.

British media reported April's friend and next door neighbour, Millie Hearne, 7, was the key witness. They had been playing together at the time.

She had raised the alarm, triggering "one of Britain's biggest child abduction searches for decades", the Telegraph said.

Another neighbour, Gwyn Briwnant-Jones, 55, said April - who has a 16-year-old sister and a 10-year-old brother - came from a loving home, and "most of the town" has been looking for her, the Daily Mail reported.

Tony Graham, 68, from Dolgellau, joined a team searching the surrounding hills and forests.

"I came down this morning after I heard what had happened on the radio. I just couldn't sit there. We did a fairly thorough search - there was more than 20 of us in my group and we were looking through bracken and forestry," he told the Mail.